Preparation of high expansion alloys



Patented Mar. 11, 1941 UNITED STATES PATENT OFFICE PREPARATION OF HIGH EXPANSION ALLOYS Reginald S. Dean and Clarence T. Anderson, Salt Lake City, Utah, alaignors to Clflcago Developmenttsompany, Chicago, 11L, a corporation of No Drawing.

Application June 12, 1940,

Serial No. 340,134

6 Claims.

This invention relates to alloys of manganese having high temperature coeflicients of expansion and is concerned in particular with alloys of I manganese, copper and nickel possessing coemcients of expansion substantially greater than that 01 brass. It also relates to methods oi treatment of such alloys in order to obtain them in a condition having unusually high coeillcients oi expansion.

We have found that ii the alloys of manganese, copper and nickel which are made in accordance with this invention, as hereinaiter described, are subjected to certain treatment, particularly combinations of mechanical and heat treatment, theirtemperature coeiilcients 0! expansion are slightly increased, and the linear relationship between length and temperature continues up to substantially higher temperatures than with alloys not subjected to the particular treatment described herein. The treatment which represents one preferred embodiment of our invention constitutes cold working the alloys so as to produce at least 25% reduction in area, heating the cold worked alloys to about 900 degrees C. for a period of about 20 minutes, and quenching in water. The cold working may be more or less severe, that is, from 10% to and the temperature from which the alloy is quenched may be varied somewhat from the optimum value of 900 degrees C., that is, from about 700 degrees C. to the melting point, without departing from our invention.

As a' specific example oi the improvement in temperature coeillcient of expansion which is obtained by the practice of the present invention, the following values have been observed for the temperature coeiilcients of expansion of rods in the cold worked condition, and after treating them in accordance with our invention:

lf'loeiiicient o expans on cold worked, 0 mo f(Joetllcient boasted to 900 om n 0 expansion agrees pos cold worked for 30 minutes and quenched in water A similar improvement in the coei'flcient of expansion of other alloys in the composition range from 50 to 85% manganese, from 2 to 35% nickel, and from 2 to 48% copper, is obtained by the application of our invention. It should also be pointed out that treatment in accordance with our invention increases the electrical resistance. The invention is particularly important because it enables the production of alloys having temperature coeiiicients of expansion as high as 27.0)(10 centimeters per centimeter per degree centigrade, having not more than 5 per cent copper. Such alloys are advantageous because they possess a higher melting point than the alloys having a higher copper content. This higher melting point makes them more suitable ior welding to low coeillclent alloys such as the nickel steels, for the manufacture of bi-metal strips used as thermostatic elements. Alloys treated in accordance with our invention retain their constancy of coefiicient of expansion up to approximately 400 degrees C.

:The manganese used in the alloys described hereinabove was electrolytic manganese having a purity of 99.9+% and the nickel and copper were also of the electrolytic grade. In order to obtain the most satisfactory results, the manganese, nickel and copper should be oi a very high grade of purity, preferably of the order of purity pointed out hereinabove.

This application is a continuation-in-part of our prior application, Serial No. 303,006, filed November 6, 1939.

What we claim as new and desire to'protect by Letters Patent of the United States is:

1. An alloy having a high coeiiicient oi expansion resulting from a treatment comprising heating the alloy in the wrought state to a temperature between about 700 degrees C. and the melting point, followed by rapid cooling, said alloy containing from 50% to 85% manganese, from 2% to 35% nickel, and from 2% to 48% copper,

- the total of the manganese, nickel and copper comprising substantially 100%.

2. An alloy having a high coefficient of expansion resulting from a treatment comprising heating the alloy in the wrought state to a temperature of approximately 900 degrees C., followed by rapid cooling, said alloy containing from about 65% to about manganese, from about 2% to about 30% nickel, and from about 2% to about 33% copper, the total oi the manganese, nickel and copper comprising substantially 100%.

3. The method of producing alloys of high coefllcient of expansion, said alloys containing from 50% to manganese, from 2% to 35% nickel, and from 2% to 48% copper, the total of the manganese, nickel and copper comprising substantially which includes the steps oi heating said alloys in the wrought state to a temperature between about 700 degrees C. and the melting point, and then rapidly cooling.

4. The method of producing alloys of high coeflicient of expansion, said alloys containing from 50% to 85% manganese, from 2% to 35% nickel, and from 2% to 48% copper, the total of the manganese, nickel and copper comprising substantially 100%, which includes the steps of cold working the alloys so as to produce at least a 25% reduction in area, heating the cold worked alloys to approximately 900 degrees C., and then rapidly cooling.

5. An alloy having a high coemcient of expansion and particularly suitable for welding to low expansion nickel steels for the manufacture of thermostatic bimetals and resulting from a treatment comprising heating said alloy to a temperature of approximately 900 degrees (3., followed by rapid cooling, said alloy containing approximately 5% copper, approximately 20% nickel, and approximately 75% manganese.

6. An alloy having 'a high coeflicient o1 expansion resulting from a treatment comprising heating the alloy in the wrought state to a temperature between about 700 degrees C. and the melting point, followed by rapid cooling, said alloy containing from about 5% to about 20% nickel, approximately 75% manganese, and the balance substantially all copper.

REGINALD S. DEAN.

' CLARENCE T. ANDERSON. 15 

